Pulumi serves as the strongest contender to Terraform when doing IaC (infrastructure as code). Terraform attempts to be a declarative markup language (HCL) but it has a lot of weird imperative quirks due to (understandably) trying to support common complex use cases. In the end they have a clunky custom language that tries to do what general programming languages have done well forever. Pulumi doesn't re-invent the wheel, and lets programming languages do what they do best. Pulumi only really cares that the programming language generates a declarative spec that can be used to compare with your infrastructure. It's the best of both worlds.